In recent, along with exhaustion of fossil fuels and environmental contamination, more interests are taken in electric vehicles or hybrid vehicles (hereinafter, generally called electric vehicles), which may be driven by means of batteries without using fossil fuels.
Batteries used for electric vehicles are mostly secondary batteries. Secondary batteries are classified into lithium series batteries and nickel-hydrogen series batteries. Lithium series batteries are mainly applied to small-sized products such as digital cameras, P-DVD, MP3P, cellular phones, PDA, portable game devices, power tools and E-bikes, and nickel-hydrogen series are mainly applied to products demanding high power such as vehicles.
Any device using a battery needs to keep insulation between the battery and the device in a good state. Bad insulation of the battery causes a leakage current, which results in various problems. For reference, a leakage current of a battery causes unexpected discharge of the battery or malfunctions of electronic equipment included in the device. Also, a leakage current of a battery employed in an apparatus using a high voltage battery such as electric vehicles may give a fatal electric shock to a person. Accordingly, in the related art, it is demanded to develop a scheme for accurately and thoroughly detecting a leakage current of a battery.